Electrical connector



Jan. 12, 1943. M. B. WOOD 2,308,436

ELEGTRICAL coNNEcToR Imed'Janl 29, 1941v fnverz for.y 7. www@ B, ung-,k

Patented Jan. 12, 1943 UNITED STATES PATENT OFFICE Chase Shawmut Company,

Newburyport,

Mass., a corporation of Massachusetts Application January 2.9, 1941, Serial No. 376,444

2 Claims.

This invention relates to electrical connectors particularly adapted although not necessarily limited to connecting the terminal of an electric fuse base with the circuit conductor.

The design of va connector for the above purpose presents diicult problems. The fuse develops heat which to a considerable extent is passed through the connector and into the conductor where it is dissipated. A solder type of connector can have its solder melted by the heat. Certain types of solderless connectors wherein a clamping screw is used to provide electrical connection can become loose under repeated heating and vcooling of the fuse under load variations. A loose connector generates heat which passes into the fuse kand can result in its premature operation.

Hence an object of the present invention is the provision of an improved form of solderless connector free from the above enumerated troubles.

Electric fuses are commonly arranged in close side by side order on a base and within a metal enclosure. The permissible spacing of the fuses is determined by the distance between the exposed conducting metal parts of the fuse circuits. Some connectors are relatively wide and hence necessitate a detrimentally rrelatively wide spacing of the fuses.

Itis an object of the present invention to provide an improved form of connector that is narrow so that the closeness of the spacing between adjacent fuses is not governed by the connector.

The connector of the present invention is particularly intended to connect a stranded cable,

composed of a bundle of small conductors, to a terminal. The current carrying capacity of a stranded cable depends upon the capacity of the individual conductor or strand of the cable. If the connector for such a cable is such that contact is made directly with but a few strands then the current of the other strands must pass through these strands and overload 'and hence heat them. Thus, for a stranded conductor it is important that the connector engage the individual strands as directly as possible, especially when used with an electric fuse. Thus, an object of the present invention is the provision of an improved form of electric connector wherein the clamping pressure spreads the strands of the cable and the parts of the connector are so constructed and arranged to make a more direct contact than heretofore with the individual strands.

A more specific object of the invention is to vcombine in vone rvconnector a high clamping pressure by the use of two clamping screws, and a large clamping extent by `using the sides of the screws to engage many of the individual strands of the conductor, the threads of which screws engage and hold the contacting strands of the conductor.

Another object of the present invention is to provide an electrical connector wherein yone of the clamping members is arranged to be flexed under clamping pressure, thus producing a contact between the .conductor and the connector that is positive under all conditions of use.

A further object of the invention is to provide a Aconnector member particularly adapted for use in connection with fuse cut-out bases and stranded conductors, wherein the connector is positioned between two clamping members and in engagement therewith when clamping pressure is applied, thus forcing the connector to spread vapart the free end portions of the strands of the conductor to such an extent that it cannot be pulled out of the connector.

A still further object of the invention is to improve generally upon the construction and operation of electrical connectors.

With the above and other objects and features in view, the invention will now be described with reference to the accompanying drawing in which:

Fig. l is a plan view of a fuse cut-out base having portions thereof out away to illustrate the construction of the connector members;

Fig. 2 is a view in cross-section taken along the line 2 2 of Fig. l;

Fig. 3 is a View in cross-section taken along the line 3 3 of Fig. l prior to applying clamping pressure to the conductor;

Fig. 4 is a detail View of the connector similar to the one illustrated in Fig. 3 but showing the parts of the connector in clamping position;

Fig. 5 is a view similar to Fig. 3 but illustrating a small conductor in position to be clamped by the connector;

Fig. 6 is a View similar to Fig. 4 but showing a small conductor of Fig. 5 clamped in the connector;

Fig. 7 is an exploded view illustrating the 'present connector;

Fig. y8 is a bottom plan viewof the top clamping plate of the present invention; and

Fig. 9 is a View in cross-section on a somewhat enlarged scale taken alo-ng the line 9-l of Fig. 8.

The present invention is illustrated as rembodied in a fuse Acut-out base of the usual construction. As illustrated, the cut-out base lo .is formed of ceramic material such, for example, as

porcelain and is provided with upstanding partition members I2 for separating the terminal connectors I4 to prevent arcing therebetween. The illustrated cut-out base is arranged to receive two ierrule type cartridge fuses I5. Since each of these cartridge receiving terminals are identical it will be necessary to describe only one terminal and connector in detail herein.

Referring now to Figs. 2 and 3 of the drawing, it will be noted that the cut-out base I is provided with a recess I S for receiving the connector and the spring clip fuse terminal I4. The spring clip terminal I4 is formed in the usual manner with a fiat intermediate base portion I8 and two arcuate side walls i9, spring-urged toward each other for receiving and clamping the end terminal I 5a of a ferrule-type cartridge fuse.

The connector 23 is provided with a base plate 22 having a left hand end portion 2I which is arranged to bear against the surface of the recess I6 and with a slightly oiiset higher parallel portion 22 which is arranged to bear against the upper face of the intermediate or base portion of the fuse clip I4. The base member 22 and the clip I4 are Xed to the base by a bolt 24 which passes through openings in the base 2i) and in the spring clip I4, the parts being held in clamping position by a nut 26 which is threaded onto the lower end of the bolt 24. It is to be noted that the base portion I3 of the fuse clip I4 is of substantially the same width as the recess I6 and hence the spring clip i4 is prevented from substantial turning movement about the bolt 24. The end 22 of the base 23 is substantially of the same width as the inside of the spring fuse clip I4. Thus, turning movement of the base 28 therein is prevented. The left hand end 2l of the base 20, as shown most clearly in the left hand portion of Fig. l, is of substantially the same width as the recess, thus further preventing any relative rotational movement between the parts. The horizontal width of the part 2l also is not materially greater than the width of the fuse clip.

The left hand end 2I of the base 20 is provided with a pair of spaced threaded openings 28 in which parallel clamping screws 3S are screwthreaded. It is to be noted that the base I8 is provided with openings 32 for receiving the lower ends of the clamping screws 3U.

The connector is provided with a steel clamping plate 34 having spaced openings 33 loosely receiving the screws 3G. The distance between the openings 28 or the openings 36 is just slightly greater than the diameter of the largest conductor which is to be used with the connector. Thus, as illustrated in Figs. 2 and 3, the conductor 38, which is stranded, occupies substantially the entire space between the clamping screws 30. Thus, when pressure is applied the conductor 38 is distorted as shown in Fig. 4 and occupies the entire area between and contacts with the base 20, the plate 34, and the clamping screws 30 and the screw threads thereof. Thus, good contact is assured between the conductor and the base 20. Furthermore, the clamping pressure is great enough to bend or ileX the clamping plate 34. Thus, the conductor 38 is resiliently held against the connector base so that good electrical contact is insured between the base 20 and the connector 33 under all conditions of expansion and contraction of the screws in response to temperature variations, the plate acting as a lock washer to prevent the screws from becoming loose. Furthermore, the strands 39 of the conductor 33 are forced against the clamping screws 30 with substantial force so that good contact is made. The friction between the strands of the conductor 38 and the screws 30 is suicient to prevent unintentional turning of the screws in an unclamping direction. The clamping pressure, as described just above, is sufhcient to cause the strands of the conductor 38 at its free end to fan or flare outwardly, as shown most clearly in the upper right hand portion of Fig. 1 at 4I, thus preventing the conductor from being pulled lengthwise out of the connector. In order further to insure that the conductor will not be pulled out of the connector, the clamping plate 34 at its bottom surface, as shown most clearly in Figs. 8 and 9, is provided with a series of serrations or teeth 40 which extend transversely of the conductor and which bite into the strands of the conductor 38 in clamping engagement therewith, thus additionally preventing lengthwise movement of the conductor 38.

While the present construction is particularly well adapted for large conductors, such as shown in Figs. 2, 3 and 4, the connector is equally effective with stranded conductors 42 of smaller size. It will be noted that, in Fig. 5 before clamping pressure is applied thereto, the conductor 42 has a diameter which is substantially less than the distance between the clamping screws 30. However, when clamping pressure is applied thereto the strands of the conductor 32 will spread sidewise and occupy the entire space between the screws 30, the clamping plate 34 and the connector base 20. Thus, with the smaller conductor 42 effective electrical connection between the connector base 29 and the end of the connector 42 is provided. The flattening of the conductor 42 also spreads or flares the free end thereof as shown in the upper part of Fig. 1 so that lengthwise movement of the conductor is prevented. Also the plate 34, having the serrations or teeth 4!) thereon, further prevents longitudinal movement. Thus, it is apparent that the connector member is fully as effective for a. small stranded conductor as it is for a large stranded conductor.

It is to be understood that while the connector described above is adapted effectively to clamp conductors of varying sizesl it is not intended that only one size of connector shall be used for all sizes of stranded electrical conductors but to use a different size of connector for each different size of fuse terminal. Thus, each size of connector will be particularly effective upon al1 different sizes of wire properly used with any particular size of fuse terminal.

It is to be noted that by having the strands of the conductor directly engage the clamping screws a large extent of contacting surface is provided, much greater than the usual cylindrical clamping recess frequently provided and the transverse width of the connector is small so that the fuses can be close together without impairment of the strike-over distance between them.

Having thus described my invention, what I claim as new and desire to secure by Letters I Patent of the United States is:

l. An electric connector comprising in combination with a bared end of a stranded conductor normally substantially circular in cross section and having the strands relatively movable, a pair of opposed substantially flat-faced clamp plates one of which is connected with a part to be conductively connected, a pair of spaced clamp screws passed through and connected electrically with said plates and spaced apart by a distance not materially greater than necessary to admit the diameter of the end of the stranded conductor to be clamped, the confronting faces of said plates with said screws defining the boundaries of a rectangular conductorreceiving space into which the end of the stranded conductor is inserted and said screws being tightened down to bring the fiat faces of said clamp plates forcibly against opposite sides of the stranded portion of the conductor thereby forcing the strand portions of the bared end out of circular arrangement and rearranging the strands into a substantially rectangular cross section engaged on the four sides by said plates and said clamp screws and with the ends of the strands substantially fanned out laterally to a greater collective width than the width between said clamp screws thus jamming the strands against the screws and preventing endwise displacement and pulling out of the conductor from between said screws and said clamp plates.

2. An electric connector comprising ln combination with a bared end of a stranded conductor normally substantially cylindrical and having the strands relatively movable, a pair of opposed substantially fiat-faced clamp plates one of which is connected with a part to be conductively connected, a pair of spaced clamp screws passed through said plates and spaced apart by a distance not materially greater than necessary to admit the diameter of the cylindrical end of the stranded conductor to be clamped, the confronting faces of said plates with said screws dening the boundaries of a substantially rectangular conductor-receiving space into which the end of the stranded cylindrical portion of the conductor is inserted and said screws being tightened down to clamp said clamp plates forcibly against top and bottom sides of the stranded portion of the conductor thereby forcing the strand portions of the bared end out of circular arrangement and rearranging the strands into a substantially rectangular cross section conductively contacted and engaged on the four sides by said plates and said clamp screws and with the ends of the strands substantially fanned out laterally to a greater collective width than the width between said said clamp screws thus preventing endwise displacement and pulling out of the conductor from between said screws and said clamp plates, one of said clamp plates being resilient and iiexing under clamping pressure of said screws and engagement with the conductor thereby maintaining clamping pressure upon the stranded conductor in contact with the threaded sides of the clamping screws and substantially frictionally locking said screws against loosening.

MORRIS B. WOOD. 

